Wireless technology has the potential to enable vehicles to communicate with each other and with the infrastructure around them. Connected vehicle technology—Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I)—could one day alert motorists of dangerous roadway conditions, impending collisions, or dangerous curves. Connected vehicles could also “talk” to traffic signals, work zones, toll booths, school zones, and other types of infrastructure.
Connected vehicle systems are based on Dedicated Short Range Communications (DSRC)—a technology similar to Wi-Fi—which is fast, secure, reliable, and unlikely to be vulnerable to interference. Using either in-vehicle or after-market devices that continuously share important safety and mobility information, vehicles ranging from cars to trucks and buses to trains would be able to “talk” to each other and to different types of roadway infrastructure.
Analyses by the U.S. Department of Transportation's National Highway Traffic Safety Administration (NHTSA) show connected vehicle technology could potentially address approximately 80 percent of the crash scenarios involving non-impaired drivers. Specifically, NHTSA research shows that this technology could help prevent the majority of types of crashes that typically occur in the real world, such as crashes at intersections or while changing lanes.
The NHTSA announced a decision in February of 2014 to begin taking steps to enable V2V communication technology for light vehicles indicating that the NHTSA may move forward with rulemaking that would require future vehicles to support V2V and V2I data communications for safety applications. Connected V2V and V2I safety applications heavily rely on the Basic Safety Message (BSM), which is one of the messages defined in the Society of Automotive standard J2735, DSRC Message Set Dictionary, November 2009. The BSM is broadcast from vehicles over the 5.9 GHz DSRC band. Transmission range is on the order of 1,000 meters. The BSM consists of two parts (Table 1). BSM Part 1 contains core data elements, including vehicle position, heading, speed, acceleration, steering wheel angle, and vehicle size and is transmitted at an adjustable rate of about 10 times per second. BSM Part 2 contains a variable set of data elements drawn from an extensive list of optional elements. They are selected based on event triggers (e.g., ABS activated) and are added to Part 1 and sent as part of the BSM message, but are transmitted less frequently in order to conserve bandwidth. The BSM message includes only current snapshots (with the exception of path data which is itself limited to a few second's worth of past history data).
TABLE 1Constituents of BSM Parts 1 and 2BSM Part 1BSM Part 2Position (local 3D):Road coefficient of frictionLatitudeRain sensor/precipitation sensorLongitudeTraction Control System active over 100 msecElevationAntilock Brake System active over 100 msecPositional accuracy Lights changed and Exterior lights (status)Motion:Wipers changed and wiper statusTransmission stateAmbient air temperaturespeedAmbient air pressureheadingVehicle type (currently only for fleet vehicles)Steering wheel angleAcceleration Set (4-way): thisincludes 3 axes of accelerationplus yaw rateVehicle Size
Although connected V2V and V2I safety applications have the potential to improve inter-vehicle communication, these applications do not address broader scenarios—specifically, Vehicle to Pedestrian (V2P) communication.